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Guide to cable railings or wire rope guardrails:

This article describes and includes illustrations of cable or wire rope railings or guardrails used along decks, balconies, walkways and stairways. We include definitions of guardrail, a handrailing or stairway handrail, and other terms that assist in understanding the building code, construction, and safety requirements that wire cable type railings must meet.

We describe the key installation features necessary for cable railings and we explain both the 4-inch sphere rule problem faced by cable railings and the ladder-effect or climbability problem that these systems must also address. Installing a cable railing according to the manufacturer's specifications for spacing, tension, support, and other parameters (described here) improve the safety of cable railings.

Where the presence of children argues against any sort of horizontally-run guard railing member, cable railing manufacturers can provide vertical cable railing designs.

What's a Railing? What's the difference between a guardrail and a handrail?

While cable "railings" are permitted under some building codes and by local building Inspectors we find that people speak a bit loosely about the definition of
"railing" - and "cable railing".

It is important to be clear in our terminology as building codes specify different requirements for handrailings than for guardrailings in terms of construction, height, and graspability. [48][49][50][51][52]

Definition of Guard railings

Properly, questions about cable railings or wire rope rails are asking about a guard rail, a type of safety "fencing" or "railing" used along the outer side of balconies
and stairways, not a "hand railing". Below in this article we discuss the installation and safety of cable-type guardrailings.

Our photo at left illustrates a home-made (and unsafe) cable guardrailing around the top of a stairwell opening in a New York home inspected by the author. The cables were visibly slack, incomplete, and the entire assembly so wobbly that it would easily collapse if leaned-on or stumbled-against.

Definition of Hand Railings

A handrail is a horizontal or sloping rail intended to be grasped by a person's hand for support when using a stairway and
importantly, instinctively grasped in an attempt to arrest a fall. Our photo above illustrates use of a wire cable "hand railing" along steps ascending the Pyramid of the Sun outside Mexico City.

Graspability of Wire or Rope Handrails

Watch out: A wire rope or wire cable in the typical dimensions used at railings (1/8-inch to 3/8-inch in diameter) is not a graspable handrailing by any of the building code standards because of its small diameter.

1003.3.3.11.3 Handrail grasp ability.

Handrails with a circular cross section shall have an outside diameter of at least 1.25 inches (32 mm) and not greater than 2 inches (51 mm) or shall provide equivalent grasp ability.

If the handrail is not circular, it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6.25 inches (159 mm) with a maximum cross-section dimension of 2.25 inches (57 mm).

Note that a "baluster" could be formed from both a rigid material (wood or metal) such as is shown in Carson Dunlop's sketch, or it might be formed by a properly-tensioned vertical cable. The purpose of balusters is to form the guarding enclosure in a stair guard or balcony guard or "guardrail". In some designs balusters also provide structural support for the handrailing or for a guardrail top member.

Typical Hand-railing heights are:

U.S. handrails for stairs with one side against a wall: 30-38"

U.S. handrails at open stairs: 34-38" above the stairs

Canadian stair handrails: 32-36" above the stairs

Wall clearance: Handrails along a wall must have at least 1.5" of clearance between the inside surface of the rail and the wall surface.

Railings should not project into the required width of the stairway by more than 4.5" at or below the handrail height above the stairs.

Specifications for Installing Cable-Type Guard Railings along Balconies or Stairways

If you take a look at cable "railing" specifications provided by a company that sells components
for cable railing construction [such as Atlantis Rail, Keuka Studios, or Wagner Companies, three suppliers of cable railing systems, you'll see that the "railing" is really a guardrail comprised of
stainless steel horizontal cables of diameters of 1/8", 5/32", 3/16", and 1/4" depending on the application.

Horizontal cables are
stretched tight, 3" o.c. to form a barrier and are supported by a combination of structural posts and intermediate posts spaced 42" o.c.
to 48" o.c. depending on the manufacturer's recommendations.

At left a wire guardrail installed at a private residence in Tivoli, NY uses individual cable tensioning devices at each end of a three-sided cable railing. Each of these little cable guardrail tensioners is secured to the wooden post with three wood screws. I'm uncertain just how much rail tension can be achieved without pulling the tensioning device right off of the post to which it was attached.

The International Residential Code (IRC) requires a minimum 36-inch-high guardrail for all decks, balconies, or screened enclosures more than 30 inches off the ground. [48][49][50][51][52]

The guardrail top height is in most jurisdictions 36" high (or more) in residential applications and 42" high in commercial installations. Along a stairway the railing height is governed by different rules because of the need to grasp the railing during use of the stairs.

Handrails are required on all stairs more than four risers in height. Handrails cannot be less than 30 inches nor more than 42 inches above the nosing of the treads

For child safety, the balusters or other decorative infill must be spaced less than 4 inches apart (a 4-inch-diameter ball should not pass between the balusters). [48][49][50][51][52]

Above (see our first photo of two just above) is an unsafe guardrailing in New York City. These horizontal cables are notably tempting for climbing by young children, and as I'll demonstrate below, keeping proper cable rail tension may be difficult enough that the opening between cables in this guardrail may be unsafe - too large.

Companies selling cable guardrailings point out that building codes (IBC and IRC) specify that the opening between vertical balusters or between
horizontal railings (if the local code official will permit them) must be close enough together that a 4-inch sphere won't pass
between them. [45][46][47]

Watch out: For horizontal guardrailing in-fill cables we point out that if the cable can be stretched or is not properly tensioned, the guardrail system may
fail this 4-inch sphere test.

In comparison, the guardrailing shown in our ship-board photo above happens to be on a Seattle ferry and resists even active jumping climbing children. The mesh guardrail infill is small enough that little toes and shoes cannot easily climb the guardrail.

Also the largest opening between the bottom-most horizontal cable or guardrail member and an individual stair tread
should not pass a 6-inch sphere. At this guardrail the opening was less than 3".

Cable or Wire Rope Spacing & Tension Are Critical for Safe Guardrails

Our photo at above left shows an attractive railing with horizontal cables intended to permit a nice view of the Brooklyn NY skyline. We also demonstrate how easily the cables can be separated as well as how attractive this guard railing is to children.

To have a chance of meeting the 4" sphere rule (maximum sphere passage <= 4 3/8") the cables must be installed with adequate tension and rigidity to prevent deflection by
climbing or playing children or other forces that might be anticipated.

If the cable spacing is more than 3" o.c.) or the cable horizontal span is too great, if the intermediate posts spaced too
far apart (more than 42" of horizontal distance o.c.), or if the cables are not adequately tensioned, the system may fail this
safety test. Using a heavier gauge cable (3/16" diameter instead of the minimum 1/8" diameter) can also add
rigidity.

The supporting structural posts and intermediate bracing also need to be strong enough to handle the forces created by properly
tensioned horizontal cables. Wagner points out that

An incredible amount of tension is generated on an end post when you have ten or more lines, each tensioned at 400 lbs. over a height of 36" to 42".

Often designers and fabricators inexperienced in cable railings will not recognize the amount of the tension applied to the posts.

The end result all too often is end posts which will bend considerably as the cables are being tensioned…or with a railing where the cables cannot be properly tensioned without an unacceptable amount of post deflection.

The posts to which hardware is mounted must be constructed so that they will not deflect perceptively as the cables are tensioned.[46]

And where we have seen
cable "guardrailings" installed, indeed a graspable and solid top rail was always provided. The top rail also provides a rigid
horizontal support that prevents the whole system from collapsing as vertical posts would bend inwards as the horizontal
cables are tightened.

Also, regular inspection of the tension and security of the cables is something I'd recommend, particularly in public
areas where the system may be subjected to climbers and pushers.

At left we illustrate that these horizontal cables were very resistant to opening, and considerable force was required to cause enough deflection to pass a 4-inch sphere. Notice that a heavier gauge cable diameter was used (3/8"), adding to the cable rail's rigidity.

But below we illustrate another (residential) cable or wire guardrailing system that was easily deflected and opened and whose tensioners appear to be of limited ability.

Atlantis points out that using a cable tensioner such as their RailEasy™ device permits on-site cable cutting to proper length and
adjustment to proper tension without risking slack sagging cables due to mis-cuts or mis-measurement. The company also
describes the proper order of tightening the tension on the horizontal cables, starting at the center cable and then
alternating above and below that point as each cable is tensioned. [45]

Just below I illustrate how easily some cable guardrail wires can be deflected with a bit of foot or hand pressure. My opinion is that even tightening these cables to a specified tension cannot predict how wide an opening might occur when children climb on the cables unless the tension specification also includes factors for both vertical post spacing intervals and the total length of wires or unsupported wires that are used in the cable guardrail.

The cable tensioners illustrated earlier in this article were part of this deflected, cable guardrail.

Other tensioning troubles occur: seeking very high tension in an effort to prevent spreading of the cables by children who may then might pass through the guardrail can bend posts or dislodge them unless the posts are of sufficient strength.

Frequently Asked Questions (FAQs)

Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.

Question: is it necessary to connect the cable guardrail to each baluster?

(May 20, 2015) Anonymous said:
does stainless cable hardware have to be placed on each baluster? How many feet of stainless cable between tighteners to create maximum tension?

Reply:

Anon I cannot answer your tension question about an unknown design, but in general the object would be to support the cable at intervals and tighten it sufficiently that it will meet the guidelines for baluster spacing, head traps, etc. The specifics for your guardrail would have to consider the cable diameter and support spacing intervals as well as area where it's to be used. Note that the article above includes other warnings.

Anon: cable guardrails that are run horizontally extend between posts, not balusters. The post spacing is not specified but rather the post spacing plus cable railing tension should be close enough and tight enough to prevent deflection that exceeds the typical baluster 4-inch spacing guideline; nevertheless, because the horizontal cables are climbable the design is still hazardous for children.

Question:

Reply:

No.

Question:

(Oct 11, 2015) jackie said:
Hi I know the cable has to be about 4" apart but does anyone know what the local code is for post to post spacing? I live in orange county CA. I've been looking and can't find that. Spacing b/t cable is easy but what about post to post? Is there a code or is it whatever you feel like spacing them?

Reply:

Post spacing is not illustrated in the model codes that we cite in this article series; rather the post spacing for cable railings will be specified by the manufacturer and are a feature of the cable railing's tensioning system. Typically you'll see more-modest intermediate posts and heavier, reinforced posts at corners where tensioning hardware is installed; on longer runs indeed a reinforced intermediate post or posts may be required for proper cable tensioning.

...

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The Home Reference Book, a reference & inspection report product for building owners & inspectors.Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

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The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.

Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: ericgalow@gmail.com or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.

ADA (Americans with Disabilities Act), Public Law 101-336. 7/26/90 is very often cited by other sources for good design of stairs and ramps etc. even where disabled individuals are not the design target.

ANSI A117.4 Accessible and Usable buildings and Facilities (earlier version was incorporated into the ADA)

[9] Falls and Related Injuries: Slips, Trips, Missteps, and Their Consequences, Lawyers & Judges Publishing, (June 2002), ISBN-10: 0913875430 ISBN-13: 978-0913875438"Falls in the home and public places are the second leading cause of unintentional injury deaths in the United States, but are overlooked in most literature. This book is unique in that it is entirely devoted to falls. Of use to primary care physicians, nurses, insurance adjusters, architects, writers of building codes, attorneys, or anyone who cares for the elderly, this book will tell you how, why, and when people will likely fall, what most likely will be injured, and how such injuries come about. "

[14] The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code. [copy on file as http://www.stairways.org/pdf/2006%20Stair%20IRC%20SCREEN.pdf ] -

[16] Mold-Resistant Building Practices, advice from an expert on how to prevent mold after a building flood and how to prevent mold growth in buildings by selection of building materials and by anti-mold construction details.

[33] Coefficient of friction of algae on surfaces [like stair treads]: Delphine Gourdon, Qi Lin, Emin Oroudjev, Helen Hansma, Yuval Golan, Shoshana Arad, and Jacob Israelachvili, "Adhesion and Stable Low Friction Provided by a Subnanometer-Thick Monolayer of a Natural Polysaccharide", Langmuir, 2008 pp 1534-1540, American Chemical Society,
retrieved 8/29/2012,Abstract: Using a surface forces apparatus, we have investigated the adhesive and lubrication forces of mica surfaces separated by a molecularly thin, subnanometer film of a high-molecular-weight (2.3 MDa) anionic polysaccharide from the algae Porphyridium sp. adsorbed from aqueous solution. The adhesion and friction forces of the confined biopolymer were monitored as a function of time, shearing distance, and driving velocity under a large range of compressive loads (pressures). Although the thickness of the dilute polysaccharide was <1 nm, the friction was low (coefficient of friction = 0.015), and no wear was ever observed even at a pressure of 110 atm over 3 decades of velocity, so long as the shearing distances were less than twice the contact diameter. Atomic force microscopy in solution shows that the biopolymer is able to adsorb to the mica surface but remains mobile and easily dragged upon shearing. The adhesion (adsorption) of this polysaccharide even to negatively charged surfaces, its stable low friction, its robustness (high-load carrying capacity and good wear protection), and the weak (logarithmic) dependence of the friction force on the sliding velocity make this class of polyelectrolytes excellent candidates for use in water-based lubricant fluids and as potential additives to synovial fluid in joints and other biolubricating fluids. The physical reasons for the remarkable tribological properties of the ultrathin polysaccharide monolayer are discussed and appear to be quite different from those of other polyelectrolytes and proteins that act as thick “polymer brush” layers.

[41] Frictional Coefficients of some Common Materials and Materials Combinations, The Engineering Toolbox, retrieved 8/29/2012, original source: http://www.engineeringtoolbox.com/friction-coefficients-d_778.html [copy on file as Friction and Coefficients of Friction.pdf ]

[42] Stairways and Ladders, A Guide to OSHA Rules, OSHA, U.S. Department of Labor, 3124-12R 2003 - Web Search 05/28/2010 original source: http://www.osha.gov/Publications/osha3124.pdf. OSHA regulations govern standards in the construction industry and in the workforce Quoting from OSHA whose focus is on workplace safety and so excludes discussion of falls and stair-falls in private homes:

OSHA estimates that there are 24,882 injuries and as many as 36 fatalities per year due to falls from stairways and ladders used in construction. Nearly half of these injuries are serious enough to require time off the job--11,570 lost workday injuries and 13,312 non-lost workday injuries occur annually due to falls from stairways and ladders used in construction. These data demonstrate that work on and around ladders and stairways is hazardous. More importantly, they show that compliance with OSHA's requirements for the safe use of ladders and stairways could have prevented many of these injuries. -osha.gov/doc/outreachtraining/htmlfiles/stairlad.html

[49] The International Building Code (IBC)
International Residential Code (IRC)

[50] ISO 9001:2008

[51] 1003.3.3.11.3 Handrail grasp ability. Handrails with a circular cross section shall have an outside diameter of at least 1.25 inches (32 mm) and not greater than 2 inches (51 mm) or shall provide equivalent grasp ability. If the handrail is not circular, it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6.25 inches (159 mm) with a maximum cross-section dimension of 2.25 inches (57 mm). Edges shall have a minimum radius of 0.125 inch (3.2 mm).

[52] BOCA National Property Maintenance Code 1993:

PM-305.5 Stairs and railings: all interior stairs and railings shall be maintained in sound condition and good repair.

Commentary: Handrails, treads and risers must be structurally sound, firmly attached to the structure, and properly maintained to perform their intended function safely. During an inspection the code official should inspect all stringers, risers, treads, and handrails.

PM-305.6 Handrails and guards: Every handrail and guard shall be firmly fastened and capable of supporting normally imposed loads and shall be maintained in good condition.

Commentary: This section provides for the safety and maintenance of handrails and guards. See Section PM-702.9 for additional requirements.

PM-702.9 Stairways, handrails and guards: Every exterior and interior flight of stairs having more than four risers, and every open portion of a stair, landing or balcony which is more than 30 inches (762mm) high, nor more than 42 inches (1067mm) high, measured vertically above the nosing of the tread or above the finished floor of the landing or walking surfaces. Guards shall be not less than 30 inches (762mm) high above the floor of the landing or balcony.

Commentary: Handrails are required on all stairs more than four risers in height. Handrails cannot be less than 30 inches nor more than 42 inches above the nosing of the treads (see Figure PM-702.9).

Guards are required on the open side of stairs and on landings and balconies which are more than 30 inches above the floor or grade below. The guard must be at least 30 inches above the floor of the landing or balcony. Guards are to contain intermediate rails, balusters or other construction to reduce the chance of an adult or child from falling through the guard. If the guard is missing some intermediate rails or balustrades, it is recommended that the guard be repaired to its original condition if it will provide protection equivalent to the protection it provided when originally constructed.

Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.

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TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & AssociatesSpecial Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.

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